diff --git a/llvm/include/llvm/Transforms/Utils/CodeExtractor.h b/llvm/include/llvm/Transforms/Utils/CodeExtractor.h
--- a/llvm/include/llvm/Transforms/Utils/CodeExtractor.h
+++ b/llvm/include/llvm/Transforms/Utils/CodeExtractor.h
@@ -110,7 +110,10 @@
     ///
     /// Based on the blocks used when constructing the code extractor,
     /// determine whether it is eligible for extraction.
-    bool isEligible() const { return !Blocks.empty(); }
+    /// 
+    /// Checks that varargs handling (with vastart and vaend) is only done in
+    /// the outlined blocks.
+    bool isEligible() const;
 
     /// Compute the set of input values and output values for the code.
     ///
diff --git a/llvm/lib/Transforms/Utils/CodeExtractor.cpp b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
--- a/llvm/lib/Transforms/Utils/CodeExtractor.cpp
+++ b/llvm/lib/Transforms/Utils/CodeExtractor.cpp
@@ -535,15 +535,41 @@
   }
 }
 
+bool CodeExtractor::isEligible() const {
+  if (Blocks.empty())
+    return false;
+  BasicBlock *Header = *Blocks.begin();
+  Function *F = Header->getParent();
+
+  // For functions with varargs, check that varargs handling is only done in the
+  // outlined function, i.e vastart and vaend are only used in outlined blocks.
+  if (AllowVarArgs && F->getFunctionType()->isVarArg()) {
+    auto containsVarArgIntrinsic = [](const Instruction &I) {
+      if (const CallInst *CI = dyn_cast<CallInst>(&I))
+        if (const Function *Callee = CI->getCalledFunction())
+          return Callee->getIntrinsicID() == Intrinsic::vastart ||
+                 Callee->getIntrinsicID() == Intrinsic::vaend;
+      return false;
+    };
+
+    for (auto &BB : *F) {
+      if (Blocks.count(&BB))
+        continue;
+      if (llvm::any_of(BB, containsVarArgIntrinsic))
+        return false;
+    }
+  }
+  return true;
+}
+
 void CodeExtractor::findInputsOutputs(ValueSet &Inputs, ValueSet &Outputs,
                                       const ValueSet &SinkCands) const {
   for (BasicBlock *BB : Blocks) {
     // If a used value is defined outside the region, it's an input.  If an
     // instruction is used outside the region, it's an output.
     for (Instruction &II : *BB) {
-      for (User::op_iterator OI = II.op_begin(), OE = II.op_end(); OI != OE;
-           ++OI) {
-        Value *V = *OI;
+      for (auto &OI : II.operands()) {
+        Value *V = OI;
         if (!SinkCands.count(V) && definedInCaller(Blocks, V))
           Inputs.insert(V);
       }
@@ -1339,27 +1365,6 @@
   BasicBlock *header = *Blocks.begin();
   Function *oldFunction = header->getParent();
 
-  // For functions with varargs, check that varargs handling is only done in the
-  // outlined function, i.e vastart and vaend are only used in outlined blocks.
-  if (AllowVarArgs && oldFunction->getFunctionType()->isVarArg()) {
-    auto containsVarArgIntrinsic = [](Instruction &I) {
-      if (const CallInst *CI = dyn_cast<CallInst>(&I))
-        if (const Function *F = CI->getCalledFunction())
-          return F->getIntrinsicID() == Intrinsic::vastart ||
-                 F->getIntrinsicID() == Intrinsic::vaend;
-      return false;
-    };
-
-    for (auto &BB : *oldFunction) {
-      if (Blocks.count(&BB))
-        continue;
-      if (llvm::any_of(BB, containsVarArgIntrinsic))
-        return nullptr;
-    }
-  }
-  ValueSet inputs, outputs, SinkingCands, HoistingCands;
-  BasicBlock *CommonExit = nullptr;
-
   // Calculate the entry frequency of the new function before we change the root
   //   block.
   BlockFrequency EntryFreq;
@@ -1426,6 +1431,8 @@
   }
   newFuncRoot->getInstList().push_back(BranchI);
 
+  ValueSet inputs, outputs, SinkingCands, HoistingCands;
+  BasicBlock *CommonExit = nullptr;
   findAllocas(SinkingCands, HoistingCands, CommonExit);
   assert(HoistingCands.empty() || CommonExit);